Telephone-repeater.



A. H. BLESSING.

TELEPHONE REPEATER.

APP-lcAvoN mso APR. 3, ma.

Patented Mar. 21, 1916.

3 SHEETS--SHLET 2.

WHA/5555i;

A. H. BLESSING.

TELEPHONE REPEATER.

APPUcAHoN HLED APR.3,1913.

1 1 76,269. Patented Mar. 21, 1916.

3 SHEETS-SHEET 3.

UNITED sTATEs PATENT oEEIoE.

ALBERT H. BLESSING, 0F FENN'IMORE, WISCOSIN, ASSIGNOR TO AUTOMATIC ELECTRIC COMPANY, CHICAGO, ILLINOIS, A CORPORATION 0F ILLINOIS.

TELEPHONE-REPEATER.

Specification of Letters Patent.

'Patented Mar. 21, 1916.

l Application filed April 3, 1913. Serial No. 758,594.

To all whom it may concern:

Be it known that I, ALBERT H. BLEssiNc, a citizen of the United States of America, and resident of F ennimore Grant county, Wisconsin, have invented a new and useful Improvement in Telephone-Repeaters,- of which vthe following is a specification.

My invention relates to an improved repeater for automatic or semi-automatic telephone systems, and it relates more speciically to a common battery two-wire repeater-that is, a repeater adapted for use in a common battery telephone system in which the automatic switches are controlled over two sides of a line circuit in series.

Among the features of my invention are to provide a repeater in which a positive and efficient operation is insured, and one in which the operation of the line relay is uniform for all-impulses. I

These and other objects and features'of my invention will be more readily understood by reference to the accompanying drawings, in which* Figures 1, 2 and 3 represent a complete connection between la calling substation A and a called substation A' in aV telephone system embodying the principles of my ini vention.

The system herein described is of Vi1. wellknown automatic type, known as a two-.

wire system,land is equipped with individual or line switches C divided into groups, each group controlledby a master switch, such as the master switch D, and also with group selectors E, repeaters F and connectors I, the operating current being supplied by the batteries Band B. The subscribers station is connected with the central oflice through the conductors 1 and 2, which terminate in a line switch C, said switch being in the group governed by the master switch D. By means of the line switch C the line is extended to the selector E, which in turn eXtendse-the connection to the repeater F. This repeater passes the impulses on to the second selector E', which operates in the same manner as the selector E to extend the connection to the connectordL which latter completes the connection to the called subscribers telephone A.

The telephone at the substation A is provided with a receiver 3, transmitter 4,

ringer 5- and condenser 6. It is also provided witli a suitable impulse-sending de- .vice similar to that shown and describedl in British Patent No. 29,654 of 1910 to..

S. G. S. Dicker, and comprises an impulse wheel 7, springs 8 and a dial (fnot shown) which has holes around its periphery for convenience in rotating. The impulse wheel 7 and the dial are secured to the same shaft, which, upon being rotated acv cording to the' digit called, opens andV closes.

the impulse springs 8.a correspondingniunber of times'to send the necessary impulses over the line.

The line switch C and the master switch D are .of the general type of line and master switches disclosed in BritishA patent-to R. W. James No. 26,301 of 1906, andniore particularly of the crm shown in British patent toT. G. Martin No. 1419 of- 1910.`

As herein represented,. Kthe line switch C comprises among other details a plunger (not shown) which is attached to the end of a socalled plunger arm 36 that is controlled by the plural-wound magnet 9. The magnet 9 is also provided with armatures 122 and 150 Yand comprises four windings,

namely, a pull-in winding 10, a holding or cut-oli winding 11, a line winding. 13 and an auxiliary Winding 12.` ,The lateral projection 151 near the center ofthe core 'of the magnet, by means of which said magnet is mounted upon the bracket 152, divides the magnetic circuit of the magnet into two parts, so that thewindingsupon one `end of the core do not have any effect upon the armatures on the other end. Of the two windings upon the upper end of the magnet only the`winding 10 is strong enough to attract the plunger arm 36 from its normal position. Although the' winding 11 is not strong enough to operate the arm 36,

it is strong enough to hold it in its operated position afterit has once been pulled down. When the plunger arm 36 is attracted by the magnet 10, the plunger point of the switch is forced into 'a group of contact springs 37, 38, 39, 40, 42, 43, 44 and 45, forcing them into contact in pairs. Although only one set of springs, viz., 37 to 45, is shown, each switch is provided with a plurality of such sets, each set forming a terminal 0f a separate trunk line leading to a selector El. These sets of trunk line terminals are, of course, multipled to corresponding sets in the banks of the other line switches in the same groups. The plungers of all of the line switches of the group which is controlled by the master switch D engage a so-called plunger shaft (not shown), and through the medium of said master switch are normally maintained opposite the terminals ,of an idle trunk line.

The master `switch consists essentially of a motor magnet 228 for rotating the ratchet wheel 229. The ratchet wheel 229 is connected with the plunger shaftin such a Inanner that a rotary motion of the ratchet wheel gives to the ,plunger shaft a reciproeating motion to carry the idle plungers backand forthfin front of their trunk terminals. To the plunger shaft there is secured a locking plate 230 providednear its outer edge with a number of openings which are adapted to beengaged by a pin 231 upon the end of the armature 2320i the relay 233. The openings in theplate 230 are so spaced that the pin 231 can engage-one of them and allow the armature 232to resume its normal position only when thev lungers of the idle i shown in British ne switches'A are direct yopposite the terminals of a trunk line, in which position it will latch the shaft. The master switch is also provided with a bank of contacts coinprising a 'ommon segment 234 and an individualco tact a for each trunk line to which the line-switches have access. The wiper 235fa1ways maintains the segment 234; in electrical connectionwith the individual 0ntactaof the trunk line before which the giungere of the idlelineswitches are being ld bythe master switch.

In'connection with the line switch C there is shown a meter J for Athe purpose of tally- -,ing the number of calls made by the calling .-,subscriben and is arranged so as not to op- -Qerate unless said calls are answered.

lvv lThe selector E is of the general type of' selector switches disclosed in United States` Letters Patent No.. 815,321, granted to Keith, Erickson & Erickson March 13, 1906,

the. circuits being) modified, however, as atent No. 141,9 of 1910, above referred to, in orderto operate in a two-wire system. It comprises among other details the line relay 14, vertical and rotary "imagnets 15 and 16 for operating the switch ,shaft and shaft wipers 19, 20 and 118, private 9,magnet 17, release relay 18 andA the side switch wipers 21, 22, 23 and 24 and the reease magnet 123. The switch shaft (not .sliown), which has a vertical and l rotary fmovement, and thev line and private wipers i118, 19 and 20 are the direct means of connection between this switch and the repeater F.

The repeater-'F has a line relay 25, a slowA relay 26 ande batteryweversing relay 27.

The line relay 25 is normally bridged across the trunk extending to the repeater from the selector E, and is arranged so that when its armature operates in accordance with the impulses from the subscribers station A, it opens and closes the bridge across the trunk extending to the selector E a corre-A ductor between otlices is eliminated.

. The trunk line extending from the repeater F terminates in a second selector E', which-is essentially the same las the selector E. This selector, as already stated, extends the line connection to the connector I, which latter is of the same type as the switches disclosed in United States Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson and Erickson, but said connector is modified and adapted to be used in a twowire system. Among other details the connector comprises the usual line relay 28, vertical and rotary magnets 29 and 30, release relay 31, release magnetl27, battery-reversing relay 32 and the ,back-bridge relay 33. Like the selector Ethis switch has the usual shaft which carries the wipers 85, 86 and 91 onto the contacts of the called subscribers line. The line switch C and the calling device at the substation A are the same as the line switch C and the calling device at the substation A. y

Having given a general description of the central office apparatus, I will now describe how'a subscriber at the substation A may obtain connection with the subscriber at substation A. We will assume that the called subscribers number is 2220. Upon the removal of the receiver3 from the switch hook the line switch is tripped in the well known manner so as to thrust its plunger into the terminal bank, thereby connecting the calling line with the first selector E by means of the springs 38 and 37, 39 and 40.

The two windings of the meter `J becomev energized when the line switch operates in a manner heretofore described, but the direction of the flow of current in each windingl opposes that in the'other, thusrendering the meter inoperative for the time being.

.folcatlei-iseleator` to be steprefturswlii' steps, in the well-known manner, opposite the row of coi'itacts in which terminate the trunk lines leading to the repeater F, whereupon the, magnet 1G operates in the usual manner to rotate the shaft wipers onto an idle trunk line to extend the line intro connection with the repeater F, thus energizing the line relay 25 in the usual manner. Upon the line. relay 25 energizing a circuit is closed Jfrom ground G throuffh the contact springs 55 and the slow relay 'i to battery l. The relay 2G. upon energizing, presses the springs 26 and 26" into contact, thereby setting` up a circuit through the winding 27h ol' the relay 2T, but, as will be shown, does not vet energize this relay. At the same time ground is put on the trunk wire 26 at (iN to supply a holding circuit for the release relay lf in the tirst selector, the original holding circuit of which is broken when the side switch passes to third position and eX- tended to theVV repeater F by wayy of the wiper 20. Furthermore. and at the same time the relay 25, by pressing together the springs 56, closes a bridge across the outgoing trunk line, thus closing a circuit` for the line relay 11' ot the sccrnd selector ll. The energization ol this relay caues the circuit of the slow acting release relay 1H" in the selector E to be closed. The circuit of the line relay 14"* is traced from ground (im through the lower winding of said relay, side switch wiper 22a, trunk line 57, through the Contact of springs 56. through an impedance coil and one of the windingsI ot' the battery-reversing relay 2T. contact of springs 55), back over the trunk line (S0. side switch wiper Q1a and through the upper winding of the line relay 111-*il to battery B. The current flowing through the winding 2T"of the relay 27 is opposed at this time by current flowing through the winding 27h over the circuit eX- tending from ground G through the spring of the relay 26 and winding 2T to battery, and the relay 27 is not operated.

The central ofiice apparatus is now in ay condition for the transn'iission oi the second series of impulses, whereupon the dial is operated in the usual manner. opening the circuit of the line relay 25 in the repeater F twice momentarily. The slow relay 26 retains its armature in an operated position during the transmission of the impulses. Therefore, the ground at (i8 is kept on the release trunk. thus holding up the preceding switches llach time an impulse is sentthat is, each `time the line relay armature drops back while the slow acting relay 26 is retaining its arniature in attracted posi tion-a circuit is completed Vfrom ground (il9 through thc contact 25 of the line relay 25 and the springs G5 of the relay 2G, and through the relay G5 to battery B. The result is that the first time the circuit is broken t'or the second digit the relay 65 closes a direct bridge across the trunk, and s ince the relay is slow acting, this bridge is maintained closed at the contacts 59 and 59 durf? mg the subsequent impulses; but the'line relay 25, each time the armature drops back in unison with the breakin ofthe circuit at the calling subscrihers te ephone, opens this bridge, thus repeating the impulses to the selectorl E. The second selector line relay 14 is thus operated, while the relea relay 18, the side switch controlling relay 18, the vertical and rotary' magnets 89l and S9", respectively, the private magnet 18 and the switching relay 52a operate just as the corresponding parts operate in the selector E, cutting the line through to the connector I and energizing the line relay of the con nector, which, upon energiaing, closes the circuit for the release relay 31, which in turn closes the holding circuit for release relay 18 at the second selector F. the holding coil 1ha of the second selector E is furnished from ground G12 through the side switch wiper 82, springs S3, through the private wiper 20, through the side switch wiper 24 and the springs of the relay 52a and through the relay 18a to battery B', thus holdingr the circuit of the release magnet 123n open. The calling device is now operated for the third digit 2, denergizing the line relay .25 at the repeater twice. rThis action iauses the deiinergization of the line relay 28 at the connector I, the armature of which falls back the same number ot' times, closing a circuit from ground GL" through the springs (Si) and T), through the private magnet control relay T1 in series with the vertical magnet 29, and through the side switch wiper T2 to battery B. The winding of the vertical magnet 29. being thus energized twice momentarily, moves the switch shaft up two steps opposite the row of contacts in which are situated the terminals of the called subscribers line. The pause in the impulses then permits the private magnet controlling relay T1 to fall back, which in turn permits the private magnet 73 to fall back. letting the side switch escape from the first to the second position. when the side switch operates thc side switch wiper 72, transferring main battery from the vertical magnet 2!) to the rotary magnet 30. The subscriber now operates his dial tor the last digit O, thus sending in ten impulses and thereby operating the line relay 25 of the repeater switch F the saine number of times, which in turn operates the line relay 2S ol the connector switch l in a manner already described. 'lhe relay now operates a correspoi'uling number of times to close a circuit through the rotary magnet 30, rotating,r the line and private wipers ten steps onto lthe contacts of the called subscribers line. Guarding potential is then placed on all the private contacts in multiple The circuit of with the one engaged from ground G11, thus preventing any other connector cutting in on the called line.

Assuming the called line to be idle, the connection is extended through to the called telephone and the ringing generator is intermittently placed across the line. Upon the subscriber at the substation A removing his receiver to answer the call the springs 100 are pressed together, thus closing thevcircuit of the back-bridge relay 33, said circuit being traced from ground G11 through the lower winding of the relay 33, springs 98 (when the ringer relay is deenergized). through the side switch wiper 8l, line wiper 86, conductor 90, through the called telephone, back over the conductor 101, line wiper 85, springs 102 and 102i, through the upper winding of the relay :53. side switch wiper 72 to battery B. 'lalking current is fed through this lastmentioned relay to'the called substation, and upon the energization of said relay a circuit is closed from ground G11 through the battery-reversing relay 32 and contact oi' springs 105 to battery B. Upon the battery-reversing relay 32 energizing, the direction oi the flow of current is changed by means of the springs of said relay, switching the negative pole of battery onto the positive side and the positive pole of battery onto the negative side of the line through the respective windings of the line relay 28. This reversal of battery current, of course, changes the direction of f'low through the winding 2T oi the double-wound relay 27 in the repeater l?. It will be remembered that up to this time the flow of current in the two windings of this relay were opposed, and although current was flowing all the time. its armature was not attracted; but immediately' upon the reversal of current through one winding the armature is pulled up to reverse the flow of current over the calling subscribers loop and through one winding of the meter magnet J in the same manner that the flow of current was reversed at the connector switch I. Now that the low of current through both of the windings of the meter is in the same direction, the armature 115 is attracted t0 register the call in the usual manner, and to shunt out, by means of the springs 120, the right-hand winding in order to keep the talking circuit balanced, leaving only7 one windin to retain the armature. After the connection is completed, the calling subscriber hangs up his receiver, thereby break-v ing the hook switch contact 121 at the sub# station A. This breaking of the contact at the springs 121 at the telephone opens the circuit of the line relay 25 at the repeater F. Upon this relay denergizing, its armature drops back, thereby breaking the circuit of the slow acting relay 26, which in turn denergizes to remove the ground potential at G8 from the release trunk, thus breaking the circuit of the holding coil 18 of the selector F. Upon the slow acting relay 18 denergizing, a circuit is closed from round G5 through the contact 50a, througi the release magnet 123 and oil'- normal springs 121 to battery B. Upon the release magnet 123 becoming energized, the usual shaft-holding pawls are withdrawn and the switch shaft is released, and by means of a spring and gravitation 1s returned immediately to its normal position, at which point it opens the contact made by the off-nor1nal springs 124, thereby opening the circuit of the release niagnet 123. The circuit of the hold-down winding 11 at the line switch C is also broken by the deenergization of the slow acting relay 18, whereupon the plunger arm 36, together with the armature 122, is released, thus retracting the plunger from the line switch bank and once more bridging the line relay 13 across the line. The windings of the meter J also dcnergize at this time, allowing the armature 115 to return to its normal condition. Thus the release of the switches preceding the repeater F is cilected by the dee'nergization of the relays 25 and 26. The denergization of the same relays 25 and 26, in addition to the above operation, causes the bridge across the called section of the trunk to be permanently opened at the springs 56, thereby breaking the circuit of the line relay 2S in the connector I, the armature ot' which falls back, thus opening the circuit of the relay 31, as well as that ot' the relay 18a of the selector E', since the holding circuit of the latter relay is transferred from ground G12 to ground G11 through the springs of the relay 28 when the side switch wiper 82 ot' the connector passes from second to third position. Upon the denergization of the coil I1811, the circuit of the release magnet 1231 is closed to return said switch to its normal condition in the same manner as that described for the selector E (Fig. 1). Upon the spring 70 of the relay 31 falling back, a circuit is closed from ground G21 through the springs 69, back contact of the spring 70, through the connector release magnet 127 and oi normal Springs 126 to battery B', thus energizing said magnet to effect the release of the connector switch I in the same manner as that of the preceding selector switches. Upon the side switch wiper 75 returning to its normal condition, the circuit from ground G11 over the conductor 128 and through the cut-off winding 7 8 of the' called subscribers line switch C is broken, which denergizes and releases the armature 129. which allows the springs of 'the contact engaged by the private wiper 91,

thus closing the circuit of the busy relay 93 over the private wiper 91, side switch wiper '75 (in second position), springs 95 and through the busy relay 93, springs 96 (when the relay 71 denergizes) and through .the

. private magnet 73 to battery. Upon energizing, the busy relay 93 closes the contact of springs 196, and a busy tone is sent back to the calling subscriber from the busy machine M by way of the side switch wiper 84., springs 98, conductor 99, through the calling subscribers telephone to the negative battery, whereupon the receiver is replaced on the switch hook and the connection is released in practically the same manner as described above.

l In connection with the repeater, it will be seen that the bridge across the line through the coils 58 and 27', together with the condensers 66 and 67, forms an inductive shunt around the line relay 25. This bridge necessarily contains an appreciable amount of impedance, so as to prevent undue leakage of voice currents from one side of the line to the other. In order to insure prompt operation of the line relays of the switches beyond the repeater in response to impulses which are transmitted t0 them by the repeater, it is necessary, or at least advisable, to exclude all impedance from the operating circuit of said relays at the repeater while impulses are being transmitted. Upon the denergization of the line relay 25 of the repeater in response to the first break in the line circuit at the substation .when any digit is called, the relay operates to remove the coils 27 and 58 from the circuit of the switch beyond the repeater by opening the contact 59, and, by closin the contact 59a, the relay 65closes a secondgbridgeacross the portion of the trunk leading to the switches beyond, which bridge is without resistance or impedance. Thus it is seen that. the line relays of the switches beyond the repeater are given an operating circuit free from resistance at the repeater, While at the saine time the shunt around the line relay 25 is not altered. Since this shunt is not altered, it insures that the line relay 25 responds to the succeeding breaks in the line circuit at the telephone with substantially the same degree of promptnes's as for the first break, thereby insuring that the im pulses delivered by the repeater shall be of substantially a uniform length, which is not always the case it the shunt around the relay 25 is removed or its impedance shortcircuited after the iirst impulse issreceived.

It will thus be seen that I have devised a very eflicient form of repeater and one which is adapted for use in various types of telephone systems. While I have illustrated the same in connection with a full automatic system of a particular type, it will be read ily apparent that my repeater is equally as well adapted for use with other types oi? automatic systems, or with semi-automatic systems. Various modifications and changes in the repeater itself will likewise be sugn gested to those skilled in the 'art and come within the broader aspects of my invention.

W'hat I claim as my invention is 1. In a telephone system, a trunk line, a repeater in said trunk for repeating impulses over the same, said repeater including a linel relay, and a permanently closed shunt circuit at the repeater around said line relay.

2. In a telephone system, a trunk line` a repeater in said trunk .for repeating iinpulses overI the same, a line relay for said repeater, and a permanently closed high impedance shunt circuit at the repeater for said line relay. v

3. In a telephone system, a trunk line, a repeater ln said trunk for repeatingr im'- pulses over the same, a line relay in said repeater bridged across said trunk, condensers in said trunk, and a permanently closed shunt circuit for said line relay at said re peater including said condensers.

4. In a telephone system, a trunk line, a repeater in said trunk for repeating impulses over the same, a line relay in said re# peater bridged across said trunk, condensers in said trunk, a permanently closed shunt circuit for said line relay at said repeater including said condensers, and an impedance coil included in said shunt.`

5. In a telephone system, a trunk line, a repeater in said trunk, a line relay for said repeater bridged across said trunk, a condenser in each side of said trunk line at said repeater, and a permanently closed shunt circuit at said repeater around said relay including both of said condensers.

6. In a telephone system. a trunk line, a repeater in said trunk, a line relay for said repeater bridged across said trunk. a condenser in each side of said trunk line at said repeater, a permanently closed shunt circuit at said repeater around said line reiay including both of said condensers. and a coil' having high impedance likewise included in said shunt. Y

7. In a telephone system, a trunk line. a repeater in said trunk for repeating inipulses over the same, a bridge across said trunk, said bridge including a line relay for said repeater and a battery, and a permanently closed shunt in said repeater around said bridge.

8. In a telephone system, a trunk line, a repeater in said trunk for repeating impulses over the same, a bridge across said trunk. said bridge including a line relay for said repeater and a battery, and a permanently closed high impedance shunt in said repeater around said bridge.

9. In a telephone system, a trunk line, a repeater in said trunk for repeating impulses over the same, a bridge across said trunk, said bridge including a line relay for said repeater and a battery, condensers in said trunk, and a permanently closed shunt in said repeater around said bridge including said condensers.

10. In a telephone system, a trunk line, a repeater in said trunk for repeating impulses over the same, a bridge across said trunk, said bridge including a line relay for said repeater and a battery, condensers in Vsaid trunk, and a permanently closed shunt in said repeater around said bridge including said condensers and a high impedance.

11. In a telephone system, a trunk line, a repeater in said. trunk for repeating impulses over the same, a line relay for said repeater bridged across said trunk, a battery connected to said bridge for supplying current to said trunk, a current-reversing relay for reversing said battery connections, and a permanently closed high impedance shunt for said line relay including a winding of said current-reversing relay.

12. In a telephone system, a trunk line, a repeater in'said trunk for repeating impulses over the same, a line relay for said repeater bridged across said trunk, a battery connected to said bridge for supplying current to said trunk, a current-reversing relay for reversing battery connections, condensers in said trunk, and a permanently closed shunt for said line relay including said condensers and a winding of said current-reversing relay.

13. In a telephone system,- a trunk line, a repeater in said trunk for repeating impulses over the same, a line relay for said repeater, an impedance coil permanently bridged across said trunk, and means for operating said line relay to thereby close a circuit to repeat impulses over said trunk, said circuit being independent of said impedance.

1l. ln a telephone system, a trunk line, a`- repeater in said trunk, condensers in the twdlsides ogsaid trunk at said repeater, a line relay for said repeater bridged across said trunk on thc incoming side of said conrdcnscrs. au impedance, a permanent shunt for said relay including said impedance and said condensers, and means controlled by said line relay for closing a repeating circuit over the outgoing side of said trunk, said repeating circuit excluding said impedance.

15. In a telephone system, a trunk line, a repeater in said trunk, a line relay for said repeater bridged across said trunk, condensers in said trunk conductively dividing said trunk in two parts7 an impedance permanently bridged across said condensers in shunt of said line relay, means for receiving impulses over the incoming end of said trunk. and means controlled by the operation of said line relay for cutting 0H said impedance bridge from the outgoing end of the trunk and for directly connecting the two sides of the trunk together. to thereby repeat impulses over the two sides of the trunk line in series.

16. In a telephone system, a trunk line, a repeater in said trunk, a line relay for said repeater, condensers in said trunk dividing the same in two parts, means for transmitting impulses over the incoming end of said trunk through said line relay to thereby operate the same, a high impedance bridge at the re eater permanently in shunt of said line re ay across said trunk. and means controlled b y the operation of said line relay for directly bridging the two sides of the second part of said trunk together, whereby all impedance is excluded at the repeater from the circuit over which the repeated impulses arc transmitted.

17. In a telephone system, a trunk line, a repeater in said trunk, a pair of condensers in said trunk at said repeater, a line relay bridged across said trunk at one side of said condensers, an impedancercoil. a permanently closed shunt for said line relay including said condensers and said impedance coil, a slow-acting relay, an energizing circuit for said relay controlled by said line relay, whereby said slow-acting relay remains energized during the intermittent operation of said line relay, means controlled by the operation of said line relay for connecting a, direct bridge across the two sides of said trunk on the other side of said condensersfor repeating impulses,` and means controlled by the operation of said slow-acting relav for eliminating all impedance at the repeater from said repeat ing circuit.

18. In a telephone system, subscribers lines, means for establishing connection between said lines` said means including trunk lines and a repeater in said trunk, a line re lay in said repeater for repeating impulses over said trunk, a battery connected to said trunk through said line relay for supplying talking current, a current-reversing relay for reversing said battery connections, said relay having a pair of energizing windings normally opposing each other, a permanently closed shunt around said line relay including a winding of said current-reversing relay and means operated upon the re sponse oi the called subscriber for revers ing the current in one of the windings of sald current-reversing relay, whereby the impedance in said shunt is increased.

19. In a telephone system, subscribers lines, a trunk line, means including an auto matic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, said repeater including a line relay, and a permanently closed shunt circuit at the repeater around said line relay.

20. In a telephone system, subscribers lines7 a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk. a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay for said repeater, and a permanently closed high impedance shunt circuit at the repeater for said line relay.

21. In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay in said repeater bridged across said trunk, con densers in said trunk, and a'permanently closed shunt circuit for said line relay at said repeater including said condensers.

22. In a telephone system, subscribers lines, a trunk line, means including an automatic 'funk-selecting switch for extending a Conner on from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end ot said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch7 a line relay in said repeater bridged across said trunk, condensers in said trunk, a permanently closed shunt circuit for said line relay at said repeater including said condensers, and an impedance coil included in said shunt.

23. In a telephone system, subscribers lines, a trunk line. means including an automatic trunk-selecting switch for extending av connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay for said repeater bridged across said trunk, a condenser in each side of said trunk line at said repeater, and a permanently closed shunt circuit at said yrepeater around said line relay including both of said condenser-s.

24. In a, telephone system, subscribers7 lines, a trunk liner` means including an automatic trunlcselecting switch for extending a connection from a calling line to said trunk, an automatic trunkselecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay for said repeater bridged across said trunk, a condenser in each side of said trunk line at said repeater, a permanently closed shunt circuit at said repeater around said line relay including both of said condensers, and a coil having high impedance likewise included in said shunt.

In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk'. a repeater in said trunk for repeating impulses to said last-mentioned switch` a bridge across said trunk, said bridge including a line relay for said repeater and a batter); and a perma nently closed shunt in said repeater around said bridge.

2d In a telephone system, sul'iscribers lines, a trunk line. means including an automatic trunlcselcctiunr switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeatingr impulses to said last-mentioned switch. a bridge across said trunk. said bridge including a line relayv 'for said repeater and a batteri'. and a perm: nently closed high impedance shunt in said repeater around said bridge.

2T. In a telephone system. subscribers lines, a' trunk line. means including an automatic trunk-selectiner switch for extcruling a connection from i calling line to said trunk, an automatic trunk-sdm-ting switch at the opposite end of said trunk. a repeater in said trunk for repeating impulses to said lastmentioned switch. a bridge across said trunk, said bridge includingr a line relay for said repeater and a battery5 condensers in said trunk, and a permanently closed shunt in said repeater around said bridge including;r said condense-rs.

28. In a telephone system` subscribers lines, a trunk line, means including an automatic trnnk-selectingr switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk` a repeater in said trunk for repeating impulses to said last-mentioned switch, a bridge across said trunk, said bridge including a line relay for said repeater and a battery, condensers in said trunk, and a permanently closed shunt in said repeater around said bridge including said condensers and a high impedance.

25).'In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunksselecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay for said repeater bridged across said trunk, a battery connected to said bridge for supplying current to said trunk, a current-reversing relay for reversing said battery connections, and a permanently closed high impedance shunt for said line relay including a winding of said current-reversing relay.

30. In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a lme relay for said repeater bridged across said trunk, a battery connected to said bridge for supplying current to said trunk, a current-reversing relay for reversing battery connections, condensers in said trunk, and a permanently closed shunt for said line relay'including said condenser-s and a winding of said current-re- -versing relay.

31. In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay for said repeater', an impedance coil permanently bridged across said trunk, and means for operating said line relay to thereby close a circuit to repeat impulses over said trunk, said circuit being independent of said impedance.

3Q. ln a telephone system, subscribers lines, a trunk line. means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk. a repeater in said trunk for repeating impulses to said last mentioned switch, condensers in the two ,sides of said trunk at said repeater, a line relay for said repeater bridged across said runl-f on the incoming side of said condensers. an impedance, va permanent shunt for said relay including said impedance and said condensers, and means controlled by said line relay for closing a repeating circuit over the outgoing side of said trunk, said repeating circuit excluding said impedance.

33. In a telephone system, subscribers lines, a trunk line, means including an automatic trunlcselecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to Said last-mentioned switch, a line relay for said repeater 4- bridged 'across said trunk, condensers in said trunk conductively dividing said trunk in two parts, an impedance permanently bridged across said' condensers in shunt of said line relay, means for receiving impulses over the incomin trunk, and means controlle by the operation of said line relay for cutting off said impedance bridge from the outgoing end of the trunk and for directly connecting the twoL sides of the trunk together, to thereby repeat impulses over the two sides of the trunk line in series.

34. In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a line relay for said repeater, condensers in said trunk dividing the same in two parts, means for transmitting impulses over the incoming end of said trunk through said line relay toA thereby operate the same, a high impedance bridge at the repeater permanently in shunt of said line relay across said trunk, and means controlled by the operation of said line relay for directly bridging the two sides of the second part of said trunk together, whereby all impedance is excluded at the repeater from the circuit over which the repeated impulses are transmitted.

35. In a telephone system, subscribers lines, a trunk line, means including an automatic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said last-mentioned switch, a pair of condensers in said trunk at said repeater, a line relay bridged across said trunk at one side of said condensers, an impedance coil, a permanently closed shunt for said line relay including said condensers and said impedance coil, a slow-acting relay, an energizing circuit for said relay controlled by said line relay, whereby said slow-acting relay remains energized during the intermittent operation of said line relay, means controlled by the operation of said line relay for connecting a end of said` -of the called subscriber for reversin direct bridge across the twovsides of said matic trunk-selecting switch for extending a connection from a calling line to said trunk, an automatic trunk-selecting switch at the opposite end of said trunk, a repeater in said trunk for repeating impulses to said lastmentioned switch, a line relay in said repeater `for repeating impulses over said trunk, a battery connected to said trunk, through said line relay for supplying talking current, a current-reversing relay for reversing said battery connections, said relay having a pair of energizing windings normally opposing each other, a permanentlyy closed'shunt around said line relay including a winding of said current-reversing relay, and means operated upon the response the current in one of the windings of sai current-reversing relay, whereby the impedance in said shunt is increased.

37. In a telephone system, a trunk line having a first and a second conductor, a condenser in each conductor, a vline relay bridged across the trunk in front of said condensers, an auxiliary relay under the control of said line relay, said auxiliary relay provided with means for disconnecting the first conductor from its condenser and for connecting it with the second conductor, and

means under the control of the line relay for breaking the circuit thus formed between the first and second conductors, said auxiliary relay provided with means for maintaining the connection between the first conductor and the condenser of the second conductor while the line relay repeats-the operation of connecting and disconnecting the second conductor from the first conductor.

38. In a telephone system, a trunk line having a first conductor and a second conductor, a line relay-associated with said line, an auxiliary relay under the control of said line relay to connect the first conductor with the second conductor, and means under the control of the line relay for repeatedly making and breaking the circuit between the first and second conductors while the auxiliary relay remains energized, and a permanently closed shunt circuit around the said line relay.

39. In a telephone system, a trunk line having a pair of conductors, a condenser in each conductor, a line relay, contact springs controlled by said relay for opening one side of said trunk, an auxiliary relay, and means controlled thereby for disconnecting the other side of said trunk from its condenser and connecting it with the condenser in the first side of said trunk.

Signed by me at Fennimore, Grant county, Wisconsin, this 26 day of March, 1913.

ALBERT H. BLESSING.

Witnesses E. J. ROETHE, J. R. VILLoMoN'rE. 

